fix: defensive SDK response handling & parts-reader normalization

- Replace all response.data ?? [] with (response.data ?? response)
  pattern across 14 files to handle SDK array-shaped responses
- Normalize SDK parts in parts-reader.ts by injecting sessionID/
  messageID before validation (P1: SDK parts lack these fields)
- Treat unknown part types as having content in
  recover-empty-content-message-sdk.ts to prevent false placeholder
  injection on image/file parts
- Replace local isRecord with shared import in parts-reader.ts

src/hooks/session-recovery/storage/thinking-strip.ts

@@ -42,7 +42,7 @@ export async function stripThinkingPartsAsync(
 ): Promise<boolean> {
   try {
     const response = await client.session.messages({ path: { id: sessionID } })
-    const messages = (response.data ?? []) as Array<{ parts?: Array<{ type: string; id: string }> }>
+    const messages = ((response.data ?? response) as unknown as Array<{ parts?: Array<{ type: string; id: string }> }>) ?? []
 
     const targetMsg = messages.find((m) => {
       const info = (m as Record<string, unknown>)["info"] as Record<string, unknown> | undefined